In order to make the optical path difference of the swing arm interferometer to change linearly with time,the swing velocity of the swing arm interferometer must be nonlinearly varied.Based on the analysis of the optical path difference(OPD) scanning system with the swing arm interferometer,the electrical characteristics of this interferometer are studied,and the OPD scanning simulation model of the interferometer is established by the saber software.To verify the OPD scanning simulation model,the PID algorithm is used for the simulation of this model,and the PID parameters are determined by studying the unit step response of the swing arm interferometer.The results show that this simulation model works well in the process of the OPD scanning,and it can provide a reference for the interferometer optical path difference scanning system design.